The t420 comes with 4G installed. I know how to add another 4G to it though the slot at the back. But I'd add as much memory as possible. So I have two questions1. Is it possible to add a secondary 8GB at the back slot? the 8G and the existing 4G won't match in size so I am not sure. Has anyone done that?2. where is the other memory slot and how to access it in case I need to match the chips up to 2x8GB.

The secondary memory slot can be accessed from the underside of the notebook, from the door provided for the purpose. The first memory module is housed under the Keyboard, and can be easily accessed. i suggest a look at the Workshop manual and a few youtube videos to see how it can be done. Easy as Pie.

I would stick to a 4X2 or 8X2 configuration, rather than have mismatched memory sizes, simply for reasons of letting both memory channels work with equal amounts of RAM. if you look elsewhere in this forum, people have successfully integrated 16 gigabytes into their T420 machines. question is the high cost of 8gb modules and the benefit a user can derive from them.

There is no problem in using 2 different manufacturer's RAM modules, as long as the Specs are the same. I use a cheap PNY 4gb module i picked up from the local BestBuy and it works perfectly. There's nothing remotely exotic about the RAM required by the Thinkpad, so it is widely available.

At present, there is only 1 piece of 4GB RAM in the system and I intend to upgrade it to the maximum – 16GB RAM.

I will be running a number of virtual systems in this baby thus I do need all the memory I could grab.

I checked out on the Kingston’s website by looking at the compatibility list. T420 does shows up with the 8GB RAM as an option. The entire listings for it will be 2GB, 4GB and 8GB. However, 8GB RAM seem to be not available, yet.

From the forum, through those who successfully installed and running the 16GB memory, it shows most of them are running on Corsair.

I am using 8gb of ram on my t410 machine, When I have choosing the ram I have looked on specification and there was info about 16 gb only at ddr4 sticks, is it possible to find ddr4 sticks now ?

Maybe anyone has the 16gb on ddr3 in t410?

regards

Unfortunately, 8gb of RAM is the maximum for your T410. I previously had a T410 and I tried to upgrade the RAM past that and the machine would POST, but not boot an OS - it couldn't address all of the memory. Sorry, but if you have 8gb of RAM you are already maxed out on the T410. It's why I sold mine and bought a T420 actually.

The only changes I made in the BIOS were to boot in legacy BIOS mode instead of UEFI or the hybrid mode (can't remember what they call it, but it was the default option). Other than that, no additional changes were required in the BIOS. I booted it, burned the recovery disks, took out the hard drive, put in the SSD, installed linux, added the ultrabay HDD adapter, formatted the 750gb drive and started moving over VM's.

I have 1 x 4 GB memory installed and i was wondering if by using 2 x 4 GB will speed up my machine when ram usage is below 4 GB on a win7 system.

If i upgrade to 1x4 gb and 1x2gb with the same clock specs will the difference in size play any part in the performance?

Thanks

It simply depends on what you are doing with the laptop. The memory is in a dual channel arrangement, so by having both slots populated, these is a performance increase during certain tasks. However, there are not many tasks where the memory is the bottleneck. It will benchmark better, but it is unlikely that you will notice an increase in speed.

I think I notice a slight improvement in overall performance. There is a clear improvement when doing intensive stuff with foto processing, etc.

My boot up times are horrid on this T420 (WIN7). I've done multiple measurements and my time is about 2 mins 40 seconds to get to the log-in window and then another 60 - 70 seconds to the desktop. I will say that shutdown times are outstanding - - probably better than any other machine I've worked on. The start up times are the worst, but I've got to deal with all sorts of stuff running that can't be skipped I played around with the Lenovo "RapidBoot Shield" program and that's bordering on worthless. In fact, I think it slowed the boot-up time. Not sure how many complete re-starts it needs to work its magic, but I've left it in place for 2 weeks and lots of re-starts and there really wasn't much improvement, if any at all

I've had problems with this Corsair memory over the past week. I had a serious BSoD event and the computer would no longer boot. During my diagnostic tests one of the memory sticks came back as FAILED. It doesn't give me any other info beyond that.

I'm RMAing both sticks back to Corsair.

Unfortunately I see others are having similar issues when you go out and read contemporary Newegg reviews of this product

Hopefully this will not jinx me, but I've had good luck with the 2x8gb Corsair sticks in my T420 for the past year. I'm sure they will get you a replacement stick and you'll be all set minus the inconvenience.

Last time I did it, I ran them for 10 hours. I usually try and do 12. Some people swear by 24 hours, but I've never done that personally. The minimum I've done for one of my own machines is 4 hours. Hope that helps.